flang: add support for llvm-6 (#8073)

* flang: add support for llvm-6

* flang: review changes

* pgmath: make flake8 happy

var/spack/repos/builtin/packages/pgmath/package.py

@@ -0,0 +1,37 @@
+##############################################################################
+# Copyright (c) 2018, Los Alamos National Security, LLC
+# Produced at the Los Alamos National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/spack/spack
+# Please also see the NOTICE and LICENSE files for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+
+from spack import *
+
+
+class Pgmath(CMakePackage):
+    """Flang's math library"""
+    homepage = "https://github.com/flang-compiler/flang"
+    url      = "https://github.com/flang-compiler/flang/archive/pgmath_20180319.tar.gz"
+
+    version('develop', git='https://github.com/flang-compiler/flang', branch='master')
+
+    conflicts("%gcc@:7.1.9999")
+    root_cmakelists_dir = 'runtime/libpgmath'